JP2012151261A - Semiconductor light-emitting element, protective film of the same, and manufacturing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor light-emitting element, a protective film of the same, and a manufacturing method of the same, capable of attaining both high migration preventing property and hydrogen blocking property.SOLUTION: In the semiconductor light-emitting element which comprises: a plurality of semiconductor layers 12 to 14 formed on a substrate 11; and electrode parts 15 and 16 and electrode parts 17 and 18 to be electrodes of the plurality of semiconductor layers 12 to 14, peripherals of the plurality of semiconductor layers 12 to 14, electrode parts 15 and 16, and electrode parts 17 and 18 are coated, as a protecting film therefor, with a SiN film 21 composed of silicon nitride whose Si-H bonding amount in the film is 1.0×10/cmor less.

Description

  The present invention relates to a semiconductor light emitting device, a protective film for the semiconductor light emitting device, and a method for manufacturing the same.

  White LED (Light Emitting Diode), which can realize energy saving and long life as a semiconductor light emitting element, is expected as a new indoor / outdoor lighting material.

JP 2006-041403 A JP 2007-189097 A

  Currently, white LEDs that can achieve both energy saving and long life are limited to the power saving type. For this reason, in order to replace existing lighting while taking advantage of low power consumption and long life, a plurality of low-power LED chips must be used, resulting in high costs.

  In order to reduce the number of LED chips used for illumination, it is necessary to increase the light output per chip. However, the LED element has a vicious cycle of heat generation and lowering of light emission efficiency, when heat is increased to increase output, heat generation increases and light emission efficiency decreases as heat generation increases. However, there is a problem that the element is destroyed or the efficiency is lowered and the life is shortened. The reason why the lifetime is shortened by heat is that, when the device is used at a high temperature, ion migration of Ag used in the electrode portion is accelerated, and the device failure due to a short circuit is likely to occur.

  Ag also accelerates migration by reacting with moisture. Therefore, when a protective film that protects Ag from moisture is used for the LED element, migration can be suppressed, which is effective in improving the reliability of the high-power element. On the other hand, the protective film is required to have high light transmittance so that light generated in the element can be efficiently extracted outside the element. This is because all of the input electric power except for the light that finally comes out becomes heat, and the element temperature is raised. Therefore, if the light transmittance of the protective film is high, the light extraction efficiency increases, the amount of current input can be reduced, and the efficiency of the element can be increased. It is also possible to suppress device failure due to heat generation or migration.

It has also been found that LED elements are deteriorated by hydrogen (including H, H ^{+ and the} like). This is because hydrogen contained in the protective film diffuses into the P-type GaN on one side of the active layer, carriers are taken up by hydrogen, and the resistance of the p-type GaN increases, so that light emission is weakened. . Further, in the process of the LED element, in order to reduce the contact resistance between the semiconductor and the metal, annealing is performed in an atmosphere containing hydrogen, which is exposed to an environment in which hydrogen is likely to be mixed.

  Here, as Conventional Example 1, the LED element structure of Patent Document 1 is shown in FIG. In FIG. 8, reference numeral 61 is a sapphire substrate, 62 is an n-type semiconductor layer made of n-type GaN, 63 is an active layer, 64 is a p-type semiconductor layer made of p-type GaN, 65 is a p-electrode, and 66 is a p-pad. 67 is an n electrode, 68 is an n pad, 71 is a SiN film, and 72 is a SiO film. The p electrode 65 has a multilayer structure made of Ag / Ni / Pt. Moreover, the arrow in a figure has shown the mode of the transmitted light.

  In the conventional LED element structure shown in FIG. 8, a highly waterproof SiN film 71 is used only on the periphery of the p-electrode 65 as a protective film, and then an SiO film 72 is formed on the entire surface. In the element structure, when Ag in the p-electrode 65 diffuses to the semiconductor side surface, the SiO film 72 has low waterproofness, so that migration easily proceeds. In general, the light transmittance of the SiN film 71 is lower than that of the SiO film 72. Therefore, the transmittance is reduced around the p-electrode 65, and the light extraction efficiency to the outside is reduced. Further, hydrogen contained in the protective film (SiN film 71, SiO film 72) diffuses to increase the resistance of the p-type semiconductor layer 64 made of p-type GaN. Further, in the LED element process, since annealing is performed in an atmosphere containing hydrogen, hydrogen is likely to be mixed, and this hydrogen diffuses to increase the resistance of the p-type semiconductor layer 64.

  Moreover, the LED element structure of patent document 2 is shown in FIG. 9 as the prior art example 2, and the problem is demonstrated. In FIG. 9, the same components as those in FIG. Moreover, the arrow in a figure has shown the mode of the transmitted light. Reference numeral 81 denotes a SiN film.

  In the conventional LED element structure shown in FIG. 9, a highly waterproof SiN film 81 is used for the entire element as a protective film. In the element structure, since the entire element is covered with the SiN film 81 having a low transmittance, the light extraction efficiency from the element to the outside is lowered. Further, hydrogen contained in the protective film (SiN film 81) diffuses to increase the resistance of the p-type semiconductor layer 64 made of p-type GaN. Further, in the LED element process, since annealing is performed in an atmosphere containing hydrogen, hydrogen is likely to be mixed, and this hydrogen diffuses to increase the resistance of the p-type semiconductor layer 64. In particular, the SiN film 81 formed under normal conditions is not dense and easily transmits hydrogen.

  Thus, in the conventional LED element structure, hydrogen reaches the inside of the LED element, and it is difficult to achieve both high migration prevention property and hydrogen blocking property.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a semiconductor light-emitting device, a protective film for the semiconductor light-emitting device, and a method for manufacturing the semiconductor light-emitting device that achieve both high migration prevention and hydrogen blocking properties.

The protective film of the semiconductor light emitting device according to the first invention for solving the above-described problems is,
In a semiconductor light emitting device having a plurality of semiconductor layers formed on a substrate and a plurality of electrode portions to be electrodes of the plurality of semiconductor layers, a protective film for protecting the semiconductor light emitting device,
As the protective film, a first protective film that covers the periphery of the plurality of semiconductor layers and the plurality of electrode portions is provided,
The first protective film is silicon nitride having a Si—H bond content of 1.0 × 10 ²⁰ [pieces / cm ³ ] or less in the film.

The protective film of the semiconductor light emitting element according to the second invention for solving the above-described problems is
In the protective film of the semiconductor light emitting element according to the first invention,
Furthermore, while providing a second protective film covering the periphery of the first protective film,
The first protective film has a thickness of 10 nm or more,
The second protective film is made of silicon oxide.

A protective film of a semiconductor light emitting element according to a third invention for solving the above-described problems is
In the protective film of the semiconductor light emitting element according to the second invention,
Furthermore, while providing a third protective film covering the periphery of the second protective film,
Similar to the first protective film, the third protective film is silicon nitride having a Si—H bond content of 1.0 × 10 ²⁰ [pieces / cm ³ ] or less, and the film thickness is It is characterized by being 10 nm or more.

A protective film of a semiconductor light emitting element according to a fourth invention for solving the above-described problems is
In the protective film of the semiconductor light emitting element according to any one of the first to third inventions,
At least one of the plurality of semiconductor layers is a semiconductor layer made of p-type GaN.

A protective film of a semiconductor light emitting element according to a fifth invention for solving the above-mentioned problems is as follows.
In the protective film of the semiconductor light emitting element according to any one of the first to fourth inventions,
At least one of the plurality of electrode portions is made of a metal containing silver.

A semiconductor light emitting device according to a sixth invention for solving the above-described problems is as follows.
A protective film for a semiconductor light emitting element according to any one of the first to fifth inventions is used.

A manufacturing method of a protective film of a semiconductor light emitting element according to a seventh invention for solving the above-described problem is as follows.
In a semiconductor light emitting device having a plurality of semiconductor layers formed on a substrate and a plurality of electrode portions serving as electrodes of the plurality of semiconductor layers, a method for producing a protective film for protecting the semiconductor light emitting device,
As the protective film, a first protective film that covers the periphery of the plurality of semiconductor layers and the plurality of electrode portions is provided, and the amount of Si—H bonds in the film is 1.0 × 10 ²⁰ [pieces / cm ³ ]. It is formed from the following silicon nitride.

A manufacturing method of a protective film of a semiconductor light emitting element according to an eighth invention for solving the above-described problems is as follows.
In the method for manufacturing a protective film of a semiconductor light emitting element according to the seventh invention,
The first protective film has a thickness of 10 nm or more,
Further, a second protective film covering the periphery of the first protective film is provided, and is formed from silicon oxide.

A manufacturing method of a protective film of a semiconductor light emitting element according to a ninth invention for solving the above-described problems is
In the method for manufacturing the protective film of the semiconductor light emitting element according to the eighth invention,
Further, a third protective film is provided to cover the periphery of the second protective film, and the Si—H bond amount in the film is 1.0 × 10 ²⁰ [pieces / cm ³ , as in the first protective film. The film is formed from the following silicon nitride, and the film thickness is 10 nm or more.

A manufacturing method of a protective film of a semiconductor light emitting element according to a tenth invention for solving the above-described problem,
In the method for manufacturing a semiconductor light emitting element according to any one of the seventh to ninth inventions,
At least one of the plurality of semiconductor layers is formed of a semiconductor layer made of p-type GaN.

A manufacturing method of a protective film of a semiconductor light emitting element according to an eleventh invention for solving the above-described problems is as follows.
In the method for manufacturing a semiconductor light emitting element according to any one of the seventh to tenth inventions,
At least one of the plurality of electrode portions is made of a metal containing silver.

  According to the present invention, in a semiconductor light emitting device, it is possible to achieve both high migration preventing property and hydrogen blocking property, which were impossible in the past, and to improve device reliability.

It is sectional drawing which shows the element structure as an example (Example 1) of the embodiment of the semiconductor light-emitting device which concerns on this invention. It is a block diagram of the plasma processing apparatus which forms the SiN film | membrane of the semiconductor light-emitting device shown in FIG. It is a graph which shows the relationship between the amount of hydrogen (Si-H bond amount) in a SiN film, and the amount of stress change. It is a graph which shows the relationship between the amount of hydrogen (Si-H bond amount) in a SiN film, and the transmittance. It is sectional drawing which shows the element structure as an example (Example 2) of the embodiment of the semiconductor light-emitting device which concerns on this invention. It is a graph which shows the relationship between the waterproofness and film thickness in the SiN film | membrane of the semiconductor light-emitting device based on this invention, and the conventional SiN film | membrane. It is sectional drawing which shows the element structure as another example (Example 3) of embodiment of the semiconductor light-emitting device which concerns on this invention. It is sectional drawing which shows the conventional LED element structure. It is sectional drawing which shows the other conventional LED element structure.

  Hereinafter, some of the embodiments of the semiconductor light emitting device, the protective film of the semiconductor light emitting device, and the manufacturing method thereof according to the present invention will be described with reference to FIGS. In the following examples, an example in which an LED is used as a semiconductor light emitting element will be described.

Example 1
FIG. 1 is a cross-sectional view showing the element structure of the LED of this example. Moreover, the arrow in a figure has shown the mode of the transmitted light.

  The LED of the present embodiment includes an n-type semiconductor layer 12 made of n-type GaN, an active layer 13 made of a multiple quantum well structure in which GaN and InGaN are alternately stacked, and a p-type made of p-type GaN. This is an element structure of a semiconductor layer in which type semiconductor layers 14 are sequentially stacked. The n-type semiconductor layer 12 and the p-type semiconductor layer 14 have a structure including an n-type contact layer and a p-type contact layer, respectively.

  Then, a part of the stacked p-type semiconductor layer 14, active layer 13, and n-type semiconductor layer 12 is removed by etching to expose the n-type contact layer of the n-type semiconductor layer 12, and the exposed portion. Then, W / Pt is sequentially stacked from the semiconductor layer side to form the n-electrode 17. On the other hand, on the upper surface of the p-type contact layer of the p-type semiconductor layer 14, a p-electrode 15 is formed by sequentially stacking Ag / Ni / Pt from the semiconductor layer side. In order to form bumps, a p-pad 16 made of Au is formed on the p-electrode 15, and an n-pad 18 made of Au is formed on the n-electrode 17. As described above, the p electrode 15 and the p pad 16, and the n electrode 17 and the n pad 18 are used as electrode portions for the stacked semiconductor layers, respectively.

  In the element structure described above, the semiconductor layer (n-type semiconductor layer 12, active layer 13 and p-type semiconductor layer 14) and electrode portion (p-electrode 15 and p-type semiconductor layer 14, except for the openings for bumps in the p-pad 16 and n-pad 18). A SiN film 21 (first protective film) is laminated so as to cover the periphery of the p pad 16, the n electrode 17 and the n pad 18). The SiN film 21 is made of SiN having an insulating property and a high hydrogen blocking property, and a protective film is formed by this one layer. As described above, the SiN film 21 protects not only the p electrode 15 containing Ag but also the entire element.

  As described above, the protective film made of SiN usually has a high waterproof property, but has a problem that the hydrogen blocking property is inferior.

  Therefore, in this embodiment, the SiN film 21 is formed using a plasma CVD (Chemical Vapor Deposition) apparatus and film formation conditions, which will be described later, so that the film quality is high and the hydrogen blocking property is high. be able to.

  First, the configuration of the plasma CVD apparatus used when forming the SiN film 21 will be described with reference to FIG. FIG. 2 shows an example of a plasma CVD apparatus for forming the SiN film 21, but as will be described later, the Si—H bond amount is reduced, the film quality is high and the hydrogen blocking property is high. Furthermore, when it is desired to improve the transmittance and withstand voltage, it is desirable to form the SiN film 21 using the plasma CVD apparatus shown in FIG. However, other plasma CVD apparatuses may be applied as long as a SiN film having a high water resistance and a high hydrogen blocking property can be formed by reducing the amount of Si—H bonds. For example, high-density plasma is used. A plasma CVD apparatus or the like is suitable.

  As shown in FIG. 2, the plasma CVD apparatus 100 includes a vacuum container 101 that maintains a high degree of vacuum. The vacuum vessel 101 includes a cylindrical vessel 102 and a ceiling plate 103, and a ceiling plate 103 is attached to the upper portion of the cylindrical vessel 102 to form a space sealed from the outside air. The vacuum vessel 104 is provided with a vacuum device 104 that evacuates the inside of the vacuum vessel 101.

  An RF antenna 105 that generates plasma is installed on the top of the ceiling plate 103. An RF power source 107 that is a high frequency power source is connected to the RF antenna 105 via a matching unit 106. That is, the RF power supplied from the RF power source 107 is supplied to the plasma by the RF antenna 105.

A gas supply pipe 108 for supplying a raw material gas or an inert gas, which is a raw material for a film to be formed, into the vacuum container 101 is installed on the upper side wall of the cylindrical container 102. The gas supply pipe 108 is provided with a gas supply amount controller for controlling the supply amount of the source gas and the inert gas. In this embodiment, SiH ₄ , N ₂ or the like is supplied as a source gas, and Ar or the like is supplied as an inert gas. By supplying these gases, plasma such as SiH ₄ , N _2, and Ar is generated above the inside of the vacuum vessel 101.

  A substrate support 110 for holding a substrate 109 that is a film formation target is installed below the cylindrical container 102. The substrate support 110 includes a substrate holding part 111 that holds the substrate 109 and a support shaft 112 that supports the substrate holding part 111. A heater 113 for heating is installed inside the substrate holder 111, and the temperature of the heater 113 is adjusted by a heater control device 114. Thereby, the temperature of the substrate 109 during the plasma processing can be controlled to 50 to 400 ° C., for example. Further, the substrate holder 111 may be provided with an electrostatic chuck mechanism that holds the substrate 109 with electrostatic force.

  The support shaft 112 is provided with a vertical drive mechanism (not shown). As shown in FIG. 2, the substrate 109 is separated from the high-density plasma region, that is, at a position not affected by the high-density plasma. A substrate 109 can be arranged. Specifically, the substrate holding unit 111 can move to a position where the distance from the lower surface of the ceiling plate 103 is 5 cm to 30 cm. For example, the substrate 109 is arranged at a position that is 10 cm or more away from the generated plasma center. To do. With this arrangement, as shown in the graph of FIG. 3 to be described later, a SiN film having a small amount of hydrogen (Si—H bond) in the film and a small amount of stress change, that is, SiN having a high hydrogen blocking property. A film can be formed.

  In the plasma CVD apparatus 100 described above, the RF power from the RF power source 107, the pressure from the vacuum device 104, the substrate temperature from the heater control device 114, the gas supply amount from the gas supply amount controller, and the vertical drive mechanism are used. A main control device 119 capable of controlling the substrate position is installed. 2 represents a signal line for transmitting a control signal from the main controller 119 to the RF power source 107, the vacuum device 104, the heater controller 114, and the gas supply amount controller.

  In the plasma CVD apparatus 100 described above, the main controller 119 controls the film formation temperature, the RF power, and the gas supply amount under the film formation conditions described later, so that the SiN film 21 having high waterproof properties and high hydrogen blocking properties can be obtained. Film formation is possible.

Therefore, next, the conditions for forming the SiN film 21 will be described. In this example, the SiN film 21 was formed with RF power: 3.0 kW, SiH ₄ : 30 sccm, N ₂ : 800 sccm, and pressure: 25 mTorr. At this time, no bias is applied to the substrate 109.

Note that this film forming condition is an example, and if it is within the following film forming condition range, characteristics without hydrogen diffusion as shown in FIG. 3 can be obtained.
Deposition temperature: 50 ° C to 400 ° C
RF power with respect to the total flow rate of SiH ₄ and N ₂ : 7 W / sccm or less Gas flow rate ratio: SiH ₄ / (SiH ₄ + N ₂ ) = 0.036 to 0.33
Bias application: None

  The graph shown in FIG. 3 shows the relationship between the amount of hydrogen in the SiN film (Si—H bond amount) and the amount of stress change after the SiN film was formed under different film formation conditions.

In FIG. 3, the amount of hydrogen in the SiN film was confirmed by IR analysis (infrared analysis, for example, FTIR). Specifically, the amount of Si—H bonds determined from the peak area of Si—H bonds generated near 2140 cm ⁻¹ was measured as the amount of hydrogen in the film (Si—H bond amount). Further, the amount of stress change of the SiN film was confirmed by a stress measuring device (for example, FLX-2320 manufactured by KLA-Tencor). Specifically, the substrate after the SiN film is formed is heated from room temperature to 450 ° C. with a heater in the stress measuring device, held at 450 ° C. for 1 hour, then lowered to room temperature, and the stress change during that time This was measured and used as the amount of stress change.

As shown in FIG. 3, the amount of stress change has a correlation with the amount of hydrogen in the film (Si—H bond amount), and the amount of stress change is large when the amount of hydrogen in the film (Si—H bond amount) is large. When the amount of hydrogen in the film (Si—H bond amount) is small, the amount of change in stress is small, and when the amount of hydrogen in the film (Si—H bond amount) is 1 × 10 ²⁰ [pieces / cm ³ ] or less, the stress change The amount is zero. This is because when the amount of hydrogen in the SiN film (especially Si-H bond hydrogen) is small, the film quality is dense and the hydrogen migration (permeation) is suppressed, so that the amount of hydrogen released by the annealing process during measurement is small. This is because the change in film stress is also reduced. That is, the stress change of the SiN film is mainly caused by the desorption of hydrogen from the film, and it can be said that there is no hydrogen diffusion if the amount of stress change is zero.

As a result of the above measurement, if the amount of hydrogen in the SiN film (Si—H bond amount) is 1 × 10 ²⁰ [pieces / cm ³ ] or less, the dense film has zero stress change and no hydrogen diffusion. It can be said that. As described above, in this example, it was impossible with the conventional SiN film by setting the amount of hydrogen (Si—H bond amount) in the SiN film to 1 × 10 ²⁰ [pieces / cm ³ ] or less. Hydrogen blocking property is made possible only with a SiN film.

  In addition, the amount of hydrogen in the SiN film (Si—H bond amount) formed by the plasma CVD apparatus shown in this example is also the transmittance of the SiN film, as shown in the experimental example in the graph of FIG. There is a correlation, and when the amount of Si—H bonds is reduced, there is also a property that the transmittance is increased. This is because there is less hydrogen, that is, impurities, in the film compared to the SiN film formed by a general plasma CVD apparatus (comparative example in the graph of FIG. 4). The attenuation coefficient k is as extremely low as 0.005 or less, and as a result, it is considered that a high transmittance is obtained.

  In addition, in the plasma CVD apparatus shown in this embodiment, as described above, high-density plasma can be generated and the substrate 109 can be separated from the high-density plasma region, so that plasma damage can be kept low. In addition, the withstand voltage can be increased as compared with a SiN film formed by a general plasma CVD apparatus.

  The film thickness of the SiN film 21 is a film thickness that can physically protect the element, that is, a film thickness that does not damage the semiconductor layer of the element. Specifically, it is used in general LEDs. 400 to 1000 nm. In such a range of film thickness, the SiN film 21 has sufficient waterproofness as can be seen from FIG.

  Therefore, in the element structure shown in FIG. 1, the entire element is covered with the SiN film 21 having the above characteristics and film thickness except for a very small part (pad opening). Intrusion of moisture can be prevented, migration of Ag in the p electrode 15 can be suppressed, and high migration prevention can be obtained.

  Moreover, since the SiN film 21 has a high hydrogen blocking property, it is possible to prevent the p-type semiconductor layer 14 made of p-type GaN from increasing in resistance and to prevent the LED element from deteriorating. Even when annealing is performed in an atmosphere containing hydrogen, the SiN film 21 can prevent hydrogen from entering the device.

  In addition, the SiN film 21 has higher transmittance and higher withstand voltage than the conventional SiN film, so that the transmittance as a protective film and the withstand voltage are improved. As a result, the SiN film 21 Since it is not necessary to increase the film thickness and the etching is unnecessary, the film formation cost can be suppressed. On the other hand, in the conventional example 1, since the SiN film 71 is formed only in the peripheral portion of the p-electrode 65, it is necessary to remove a part of the SiN71 film on the whole before forming the SiO film 72, and the film formation cost is increased. In addition, in the conventional example 2, the SiN film 81 generally has a lower withstand voltage than the SiO film, so that it is necessary to increase the film thickness in order to ensure insulation, and the time for film formation is long. Film formation costs are increased.

  Regarding the hydrogen blocking property, migration preventing property, transmittance and insulation resistance, the above results are summarized and shown in Table 1 when compared with Conventional Example 1 and Conventional Example 2 described above. In Table 1, Example 2 and Example 3 described later are also shown.

  As shown in Table 1, the hydrogen blocking property in this example is higher than those of Conventional Example 1 and Conventional Example 2 because the SiN film 21 is dense. In addition, the migration preventing property in this example is higher than that of Conventional Example 1 and equivalent to that of Conventional Example 2 because the entire element is covered with the SiN film 21. As a result, the reliability of the element is improved.

  The transmittance (compared under the conditions of a film thickness of 500 nm and a light wavelength of 350 nm) in this example is about the same as or higher than that of Conventional Example 2. In addition, since the withstand voltage in this embodiment is higher than that of the conventional example 2, it is not necessary to increase the film thickness of the SiN film 21 and the etching is not required. The film formation cost can be reduced as compared with the conventional example 2 in which the film thickness is increased.

  Thus, in this example, it is possible to achieve both high migration prevention and hydrogen blocking properties, and as a result, the reliability of the LED element can be improved.

(Example 2)
FIG. 5 is a cross-sectional view showing the element structure of the LED of this example. In FIG. 5, the same reference numerals are given to the same components as those shown in the first embodiment (see FIG. 1), and duplicate descriptions are omitted. Moreover, the arrow in a figure has shown the mode of the transmitted light.

  In the LED of this example, the element structure of the semiconductor layer has the same configuration as the LED shown in Example 1 (see FIG. 1). Further, as in the first embodiment, a protective film is formed so as to cover the periphery of the semiconductor layer and the electrode portion except for the openings for the bumps in the p pad 16 and the n pad 18. The structure of the film is different from that of Example 1.

  Specifically, as the protective film, an SiN film 31 (first protective film) made of SiN having insulating properties and high hydrogen blocking properties, and an SiO film 32 (second protective film) made of SiO having insulating properties. Film). That is, a protective film having a two-layer structure in which the first layer is the SiN film 31 and the second layer is the SiO film 32 is formed. Thus, not only the periphery of the p electrode 15 containing Ag but also the entire periphery of the device is protected by the two-layer structure of the SiN film 31 and the SiO film 32.

  Of these SiN film 31 and SiO film 32, the SiN film 31 is formed by the plasma CVD apparatus and film forming conditions described in the first embodiment. On the other hand, the SiO film 32 may be a plasma CVD apparatus as shown in FIG. 2, but may be another plasma CVD apparatus, and a plasma CVD apparatus using high-density plasma is also preferable. If a similar SiO film can be formed, other apparatuses such as a sputtering apparatus and a vacuum evaporation apparatus can be used.

  As described above, the protective film made of SiN usually has a high waterproof property, but has a problem that the transmittance is low and the hydrogen blocking property is poor. Further, the SiN film shown in Example 1 has high waterproofness and hydrogen blocking property, but the transmittance and withstand voltage are not as high as those of the SiO film, and there is room for improvement.

  Therefore, in this example, as described in Example 1, the SiN film 31 has a high hydrogen blocking property by reducing the amount of Si—H bonds. Further, a SiO film 32 having a high transmittance and a high withstand voltage is laminated outside the SiN film 31, and the thickness of the SiO film 32 is made thicker than that of the SiN film 31. With such a configuration, the transmittance and the withstand voltage are improved. However, the SiO film 32 originally has a property that it is easy to pass and hold water, and once it contains a large amount of moisture, it becomes a moisture supply source and water may enter the element side.

  Therefore, in this embodiment, the SiN film 31 has a film thickness that can maintain waterproofness. Here, with reference to the graph of FIG. 6, the relationship between the waterproofness and film thickness in the SiN film 31 will be described. In FIG. 6, as a comparative example, a graph of waterproofness and film thickness in SiN formed by a general plasma CVD apparatus is shown with dotted lines. Note that the waterproof property in FIG. 6 means that as a sample, a SiN film to be evaluated and a SiO film with a large amount of water in the film are sequentially formed on a cobalt-iron film. By measuring the degradation, the waterproof property of the SiN film to be evaluated is evaluated.

  As shown in the graph of FIG. 6, in the comparative example, when the film thickness of the SiN film is less than 35 nm, the waterproofness decreases as the film thickness decreases, but the film thickness of the SiN film is 35 nm or more. In this case, it can be seen that the waterproof property is good. On the other hand, in this example, when the film thickness of the SiN film is less than 10 nm, the waterproof property decreases as the film thickness decreases. However, when the film thickness of the SiN film is 10 nm or more, the waterproof property is reduced. It turns out that it is favorable. Thus, in the comparative example, good waterproofness could not be obtained unless the thickness was 35 nm or more, but in this example, good waterproofness is obtained by setting the thickness of the SiN film 31 to 10 nm or more. be able to. That is, in the SiN film 31, a thickness of 10 nm or more is a film thickness that can maintain waterproofness.

  As described above, the dense SiN film 31 is provided inside the SiO film 32 so as to maintain a waterproof property. In particular, the moisture supplied from the SiO film 32 is blocked to reduce water intrusion into the LED element. is doing.

  Further, the total film thickness of the SiO film 32 and the SiN film 31 is set to a film thickness that can physically protect the element, that is, a film thickness that does not damage the semiconductor layer of the element. Specifically, the total film thickness is set to 400 to 1000 nm used in general LEDs.

  In the element structure shown in FIG. 5, the entire element is covered with the SiN film 31 having the above characteristics and film thickness except for a very small part (pad opening). Can be prevented, and migration of Ag in the p-electrode 15 can be suppressed, and high migration prevention can be obtained.

  Further, since the SiN film 31 has a high hydrogen blocking property, it is possible to prevent the p-type semiconductor layer 14 made of p-type GaN from increasing in resistance and to prevent the LED element from deteriorating. Even when annealing is performed in an atmosphere containing hydrogen, the SiN film 31 can prevent hydrogen from entering the element.

  In addition, since the SiO film 32 having a high transmittance and a high withstand voltage is laminated with a film thickness thicker than that of the SiN film 31, the transmittance of the entire protective film and the protective film are compared with the case of using only the SiN film. Overall breakdown voltage is improved. Furthermore, since it is not necessary to increase the thickness of the SiN film 31 and the etching is not required, the deposition cost can be reduced.

  Therefore, as shown in Table 1, the hydrogen blocking property in the present example is higher than those of Conventional Example 1 and Conventional Example 2 because the SiN film 31 is dense. Further, the migration preventing property in this embodiment is higher than that of the conventional example 1 because the entire element is covered with the SiN film 31. As a result, the reliability of the element is improved.

  Further, the transmittance in this example is compared under the conditions of a film thickness of 500 nm and a light wavelength of 350 nm (however, the film thickness of the SiN film 31 of this example is 10 nm and its transmittance is 99.97%). The transmittance of the entire protective film is 99.97%. This transmittance is substantially the same as Conventional Example 1 (when the transmittance in the vicinity of the p electrode is also taken into consideration), which is higher than Conventional Example 2 and Example 1, and the light extraction efficiency is improved. This is because the SiN film 31 having a low transmittance is thinner than the entire protective film and the SiO film 32 having a high transmittance is thick, so that a high transmittance can be obtained in the entire protective film. Because.

  Thus, in this example, both high migration prevention and hydrogen blocking properties can be achieved, and high transmittance can also be achieved. As a result, the reliability of the LED element is improved, A high luminance structure can be realized.

(Example 3)
FIG. 7 is a cross-sectional view showing the element structure of the LED of this example. In FIG. 7, the same components as those shown in the first embodiment (see FIG. 1) are denoted by the same reference numerals, and redundant description is omitted. Moreover, the arrow in a figure has shown the mode of the transmitted light.

  In the LED of this example, the element structure of the semiconductor layer has the same configuration as the LED shown in Example 1 (see FIG. 1). Further, as in the first embodiment, a protective film is formed so as to cover the periphery of the semiconductor layer and the electrode portion except for the openings for the bumps in the p pad 16 and the n pad 18. The structure of the film is different from that of the first and second embodiments.

  Specifically, as the protective film, an SiN film 41 (first protective film) made of SiN having insulating properties and high hydrogen blocking properties, and an SiO film 42 (second protective film) made of insulating SiO. Film) and an SiN film 43 (third protective film) made of SiN having insulating properties and high hydrogen blocking properties are sequentially stacked. That is, a protective film having a three-layer structure in which the SiN film 41 is the first layer, the SiO film 42 is the second layer, and the SiN film 43 is the third layer is formed. In this way, not only the periphery of the p electrode 15 containing Ag but also the periphery of the entire device is protected by the three-layer structure of the SiN film 41, the SiO film 42, and the SiN film 43.

  Of these SiN film 41, SiO film 42, and SiN film 43, SiN films 41 and 43 are formed by the plasma CVD apparatus and film forming conditions described in the first embodiment. On the other hand, the SiO film 42 may be a plasma CVD apparatus as shown in FIG. 2, but may be another plasma CVD apparatus, and a plasma CVD apparatus using high-density plasma is also preferable. If a similar SiO film can be formed, other apparatuses such as a sputtering apparatus and a vacuum evaporation apparatus can be used.

  As described above, the protective film made of SiN usually has a high waterproof property, but has a problem that the transmittance is low and the hydrogen blocking property is poor. Further, the SiN film 21 shown in Example 1 has high waterproofness and hydrogen blocking properties, but the transmittance and withstand voltage are not as high as those of the SiO film, and there is room for improvement. In addition, the protective film having the two-layer structure composed of the SiN film 31 and the SiO film 32 shown in the second embodiment has a waterproof property and a hydrogen blocking property as the SiN film 31. Once a large amount of water is contained, it becomes a water supply source and may also become a hydrogen supply source, and there is a risk that water and hydrogen may invade into the device side over a long period of time. .

  Therefore, in the present embodiment, as described in the first embodiment, the SiN film 41 is reduced in the amount of Si—H bonds to increase the hydrogen blocking property and is described in the second embodiment (FIG. 6). As described above, the film thickness is 10 nm or more so that waterproofness can be maintained. Further, on the outside of the SiN film 41, an SiO film 42 having a high transmittance and a high withstand voltage is laminated while being inferior in waterproofness, and the thickness of the SiO film 42 is made thicker than that of the SiN film 41. With such a configuration, the transmittance and the withstand voltage are improved. Further, a SiN film 43 having a film thickness of 10 nm or more that has a high hydrogen blocking property and a waterproof property is laminated on the outside of the SiO film 42.

  As described above, the dense SiN film 41 is provided inside the SiO film 42 so as to maintain the waterproof property. In particular, moisture and hydrogen supplied from the SiO film 42 are blocked, and the outside of the SiO film 42 is provided. Since the dense SiN film 43 is provided to maintain a waterproof property, the penetration of moisture and hydrogen into the SiO film 42 from the outside is blocked, and the penetration of moisture and hydrogen into the LED element is reduced.

  In addition, the total film thickness of the SiN film 41 and the SiN film 43 in the SiO film 42 is a film thickness that can physically protect the element, that is, a film thickness that does not damage the semiconductor layer of the element. Specifically, the total film thickness is set to 400 to 1000 nm used in general LEDs.

  In the element structure shown in FIG. 7, the entire element is covered with the SiN film 41 having the above characteristics and film thickness except for a very small part (pad opening). Can be prevented, and migration of Ag in the p-electrode 15 can be suppressed, and high migration prevention can be obtained. Further, in this embodiment, since the SiN film 43 is further provided outside the SiO film 42, moisture entering the protective film, in particular, the inside of the SiO film 42 can be reduced. It is possible to reduce the moisture that enters the water. As a result, it was possible to further improve the migration prevention property as compared with Example 2.

  Further, since the SiN films 41 and 43 have high hydrogen blocking properties, it is possible to prevent the p-type semiconductor layer 14 made of p-type GaN from increasing in resistance and to prevent the LED element from deteriorating. Even when annealing is performed in an atmosphere containing hydrogen, the SiN films 41 and 43 can prevent double penetration of hydrogen into the element.

  In addition, since the SiO film 42 having a high transmittance and a high withstand voltage is stacked with a film thickness thicker than that of the SiN films 41 and 43, the transmittance of the entire protective film, compared with the case of only the SiN film, The withstand voltage of the entire protective film is improved. Furthermore, it is not necessary to increase the thickness of the SiN films 41 and 43 as in the prior art, and the etching is unnecessary, so that the film formation cost can be reduced.

  Therefore, as shown in Table 1, the hydrogen blocking property in this example is higher than that of Conventional Example 1 and Conventional Example 2 because the SiN films 41 and 43 are dense and double-layered. It becomes higher than Example 2. Further, the migration preventing property in this embodiment is higher than that of the conventional example 1 because the entire element is covered with the SiN film 41 and the SiO film 42 is further covered with the SiN film 43. Is also expensive. As a result, the reliability of the device is further improved.

  Further, the transmittance in this example is a case where the film thickness is 500 nm and the light wavelength is 350 nm (however, the film thickness of the SiN films 41 and 43 in this example is 10 nm and the transmittance is 99.97%). The transmittance of the entire protective film is 99.94%. This transmittance is substantially the same as Conventional Example 1 (when the transmittance near the p-electrode is also taken into consideration) and Example 2, and is higher than Conventional Example 2 and Example 1, and the light extraction efficiency is improved. As in the second embodiment, the thickness of the SiN films 41 and 43 with low transmittance is smaller than the thickness of the entire protective film, and the thickness of the SiO film 42 with high transmittance is thick. This is because a high transmittance can be obtained.

  Thus, in this example, both high migration prevention and hydrogen blocking properties can be achieved, and high transmittance can also be achieved. As a result, the reliability of the LED element is further improved. A high brightness structure can be realized.

  In Examples 1 to 3, the material and configuration of the semiconductor layer of the LED is not limited to the above-described configuration as long as at least one semiconductor layer includes p-type GaN that has high resistance by hydrogen. Other materials and configurations may be used. For example, the active layer 13 may be a nitride semiconductor composed of group III atoms such as In, Al, and Ga and group V atoms N, and is not limited to a multiple quantum well structure. A well structure or a strained quantum well structure may be used. The substrate 11 is not limited to a sapphire substrate, but may be a GaN substrate. Also, the manufacturing method of each semiconductor layer is also a known manufacturing method such as metal organic vapor phase epitaxy (MOVPE) or metal organic chemical vapor deposition (MOCVD). Can be used.

  Further, the p electrode 15 has a multilayer structure, but may include a metal other than Ni and Pt as long as it contains a metal such as Ag or Cu that may cause migration. Moreover, the manufacturing method can use a well-known manufacturing method, for example, sputtering method, a vacuum evaporation method, etc., It forms in a desired pattern by the lift-off method after lamination | stacking, for example. Conventionally, in consideration of migration of Ag or the like, a multilayer structure (sandwich structure) in which upper and lower layers such as an Ag layer are composed of other metals was sometimes used. Since the entire element is covered, migration of Ag or the like can be sufficiently suppressed without necessarily adopting such a sand structure.

  Further, the p pad 16, the n electrode 17, and the n pad 18 have a single layer structure or a multilayer structure, and the manufacturing method is the same as the p electrode 15, for example, a known manufacturing method such as sputtering or vacuum deposition. For example, a desired pattern is formed by a lift-off method after stacking.

Note that silicon nitride is typically Si ₃ N ₄ , and may be expressed as Si _x N _y depending on the composition ratio, but here, for simplicity of description, it is described as SiN. did. Similarly, a representative example of silicon oxide is SiO ₂ , which may be expressed as Si _x O _y depending on the composition ratio, but here it is described as SiO for the sake of simplicity. .

  The present invention is applied to a semiconductor light emitting device, and is particularly suitable for a white LED.

11 substrate 12 n-type semiconductor layer 13 active layer 14 p-type semiconductor layer 15 p-electrode (electrode part)
16 p pad (electrode part)
17 n electrode (electrode part)
18 n pad (electrode part)
21, 31, 41 SiN film (first protective film)
32, 42 SiO film (second protective film)
43 SiN film (third protective film)

Claims (11)

In a semiconductor light emitting device having a plurality of semiconductor layers formed on a substrate and a plurality of electrode portions to be electrodes of the plurality of semiconductor layers, a protective film for protecting the semiconductor light emitting device,
As the protective film, a first protective film that covers the periphery of the plurality of semiconductor layers and the plurality of electrode portions is provided,
A protective film for a semiconductor light-emitting element, wherein the first protective film is silicon nitride having a Si—H bond amount of 1.0 × 10 ²⁰ [pieces / cm ³ ] or less in the film. In the protective film of the semiconductor light emitting device according to claim 1,
Furthermore, while providing a second protective film covering the periphery of the first protective film,
The first protective film has a thickness of 10 nm or more,
A protective film for a semiconductor light-emitting element, wherein the second protective film is made of silicon oxide. In the protective film of the semiconductor light-emitting device according to claim 2,
Furthermore, while providing a third protective film covering the periphery of the second protective film,
Similar to the first protective film, the third protective film is silicon nitride having a Si—H bond content of 1.0 × 10 ²⁰ [pieces / cm ³ ] or less, and the film thickness is A protective film for a semiconductor light-emitting element, characterized by being 10 nm or more. In the protective film of the semiconductor light-emitting device according to claim 3,
A protective film for a semiconductor light emitting element, wherein at least one of the plurality of semiconductor layers is a semiconductor layer made of p-type GaN. In the protective film of the semiconductor light emitting element according to any one of claims 1 to 4,
A protective film for a semiconductor light-emitting element, wherein at least one of the plurality of electrode portions is made of a metal containing silver.   6. A semiconductor light emitting device comprising the protective film for a semiconductor light emitting device according to any one of claims 1 to 5. In a semiconductor light emitting device having a plurality of semiconductor layers formed on a substrate and a plurality of electrode portions serving as electrodes of the plurality of semiconductor layers, a method for producing a protective film for protecting the semiconductor light emitting device,
As the protective film, a first protective film that covers the periphery of the plurality of semiconductor layers and the plurality of electrode portions is provided, and the amount of Si—H bonds in the film is 1.0 × 10 ²⁰ [pieces / cm ³ ]. A method for manufacturing a protective film of a semiconductor light-emitting element, comprising forming the following silicon nitride. In the manufacturing method of the protective film of the semiconductor light-emitting device according to claim 7,
The first protective film has a thickness of 10 nm or more,
Further, a method for producing a protective film of a semiconductor light emitting element, comprising providing a second protective film covering the periphery of the first protective film, and forming the protective film from silicon oxide. In the manufacturing method of the protective film of the semiconductor light-emitting device according to claim 8,
Further, a third protective film is provided to cover the periphery of the second protective film, and the Si—H bond amount in the film is 1.0 × 10 ²⁰ [pieces / cm ³ , as in the first protective film. A method for manufacturing a protective film for a semiconductor light-emitting element, characterized in that the protective film is formed from the following silicon nitride and has a thickness of 10 nm or more. In the manufacturing method of the protective film of the semiconductor light emitting element according to claim 9,
A method for manufacturing a protective film of a semiconductor light emitting element, wherein at least one of the plurality of semiconductor layers is formed of a semiconductor layer made of p-type GaN. In the manufacturing method of the protective film of the semiconductor light-emitting device according to any one of claims 7 to 10,
A method for producing a protective film of a semiconductor light emitting element, wherein at least one of the plurality of electrode portions is made of a metal containing silver.

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